1. Field of the Invention
This invention relates to a hydraulically operated gravitational processing apparatus and method which recovers a concentrated product containing dense or heavy mineral particles in smaller sizes than obtainable with similar equipment of the prior art. More particularly, this invention relates to such an apparatus and process in which boundary wall or surface effects on fluid flow are utilized to separate relatively light mineral particles from relatively dense or heavy mineral particles, such as in mineral processing.
2. Description of the Prior Art
It is known in the prior art to use an inclined conduit or tube to separate relatively heavy mineral particles from relatively light mineral particles using fluid flow through the inclined conduit or tube. Such apparatus and its operation is taught, for example, in U.S. Pat. Nos. 2,946,439 and 3,240,336, which are commercially known as the Lavodune and Lavoflux, respectively.
The apparatus described in these two patents includes an elongated inclined tubular or pipe-like conduit through which a fluid flows in upward direction The feed mixture of different density particles is initial introduced into the fluid flow at an intermediate longitudinal location of the inclined conduit. During the subsequent processing, the denser or heavy mineral particles resultantly move in downward direction, in counter direction to the fluid flow, and discharge as concentrates from a lower location of the inclined conduit. Meanwhile, the less dense or light mineral particles resultantly move in the upward direction, and along with the fluid flow are discharged as tailings from the upper terminus of the inclined conduit.
The Lavodune processing method is specifically based on a turbulent condition of fluid flow in which the velocity is regulated between the settling rates of the different density particles. With an appropriate incline of the conduit at approximately 50 to 55 degrees, the particles introduced into the fluid flow are more or less strongly agitated according to different particle densities. The Lavodune processing method recovers heavy mineral particles which include a minimum size of nominally 500 microns.
The Lavoflux processing method is specifically based on a laminar condition of fluid flow in which the velocity is regulated between the entrainment velocities of the different density particles. At an appropriate incline of the conduit of approximately 50 to 60 degrees, the introduced particles are more or less retained in fluid flow suspension throughout the entire processing length of the inclined conduit. The Lavoflux processing method recovers heavy mineral particles which include a minimum size of nominally 70 microns.
While these prior art apparatuses have had some significant commmercial application, a substantial portion of mineral processing includes particles of smaller sizes than included within the above operating ranges. Further technical improvement in such processing or apparatus is required to separate smaller particles according to different relative densities.